I finally arrived in Copacabana, which I visited after I'd been to Tiwanaku during my trip to Bolivia, after a journey in a taxi van lasting many hours. The route you take to get to Copacabana is quite wonderful. Before you reach the town, you have to stop at San Pedro de Tiquina and cross the lake on one of the small ferries there capable of carrying cars and buses.
Copacabana is quite a tourist-oriented town due to the presence of the islands Isla del Sol and Isla de la Luna out in lake Titicaca. It therefore contains a large number of restaurants and souvenir shops. The owners take advantage of this a little by inflating the prices. There are several boat services to the two islands. It is quite a slow trip however, so make sure you allow enough time!